This invention relates to a system which includes a flexible hose for transmitting hazardous materials. In a typical application, the hazardous material, such as propane or anhydrous. ammonia, is transmitted by the flexible hose system from a fixed storage tank to tank mounted on a roadway vehicle to a fixed storage tank.
Various arrangements have been made for transferring hazardous materials between a portable roadway vehicle tank and a fixed storage tank. Since the release of the hazardous material could result in a life threatening situation, special precautions are taken to insure that little if any hazardous material is released to the atmosphere during transfer of the material along a flexible hose assembly that connects a fixed tank to the portable tank in the event of a complete hose failure. U.S. patent application Ser. No. 09/518,535 filed on Mar. 4, 2000 discloses an improved system for loading and unloading tanks containing hazardous fluids.
One of the drawbacks to the above system is that the system components involved in the transfer of the material between the tanks are located partially along the flexible hose which extends between the tanks, and partially on the vehicle or the portable tank connected to the vehicle. Accordingly, the system must be engineered for operating with various styles of trailers, and each variation must be certified by an engineer certified with the Department of Transportation or similar governmental agency. Since there are many styles of trailers and portable tanks, each variation much be tested to obtain certification, and the cost of these tests can be significant to the system developer. Also, the system must be inspected at installation by a certified governmental agency inspector, thereby further increasing the cost and inconvenience to the trailer owner.
One prior art system marketed by Smart-Hose Technologies, Inc. utilizes an internally coated cable which normally unseats valve members located at each end of the cable. In the event of hose separation, the valve members are released to stop the flow of product in both directions. The cable acts as a spring to maintain the valves off their seats, and the separation of the cable is intended to release the biasing force on the valves, which then move to the closed position. The biased cable which extends between the ends of the hose is installed with the hose during manufacture, so that the user must purchase the assembly which includes the hose. In addition, the operational integrity of the system cannot be readily confirmed, since there is no ability to check whether one of the valves has been frozen in the opened position. During handling and coiling of the hose, special care must be taken not to bend the hose and thus the cable over a sharp radius, or the cable will lose its ability to hold the valves open. If there is a failure of the hose, the entire system must be replaced, not merely the separated hose.
The disadvantages of the prior art are overcome by the present invention, and an improved flexible hose system for transmitting hazardous fluid, such as propane or anhydrous ammonia, is hereinafter disclosed.
The present invention uses a flexible hose system for transmitting hazardous fluid from a portable tank to a stationary tank or from a stationary tank to a portable tank, or between two portable tanks. Since all of the components are provided on the hose assembly and are not installed as a component of or secured to the trailer, the portable tank, or the fixed tank, regulations allow the hose assembly to be certified and then used by trailer operators regardless of the variation in the trailer or portable tank design. The hose assembly of the present invention thus need not be installed as a part of the trailer equipment, and rather is merely carried by the trailer operator and used during off loading or on loading independent of the equipment on the trailer. Accordingly, the flexible hose system may be certified one time by a certified governmental agency engineer, and the system need not be inspected by a certified governmental inspector at installation time.
It is an object of the present invention to provide an improved flexible hose assembly for interconnecting a portable tank with either a stationary tank or another portable tank when transmitting hazardous fluids between the tanks. The hose assembly includes a back check housing containing a valve and a seating surface, with the flexible hose extending downstream from the back check housing. The piston interconnected with the back check housing is axially movable between a locked position and an unlocked position, and is responsive to fluid pressure in a flexible sensing line which extends downstream from the back check housing within the hose. Fluid pressure in the hose is thus transmitted through the sensing line to move the piston to the locked position, thereby maintaining the valve member in the back check housing in the open position.
It is a further object of the invention to provide an improved method of interconnecting a portable tank with another tank, wherein pressure in a downstream portion of a flexible hose is used to maintain a piston in a locked position, which thereby maintains a valve member in the back check housing in the open flow position. Product flow may be initiated by manually moving the valve member to the open flow position, and then releasing the valve member only after the pressure in the flexible hose is sufficient to maintain the piston in the locked position.
It is a feature of the invention that a check valve be positioned within a downstream portion of the flexible hose assembly for preventing fluid flow back through the flexible hose.
It is a further feature of the invention that the valve member may be biased closed both by fluid being transmitted through the flexible hose assembly and by a spring which biases the valve member toward engagement with the seat.
It is a further feature of the invention to utilize a plurality of ball members for cooperating with the piston to maintain the valve member open when the piston is in the locked position and for allowing the valve member to move to the closed position when the piston is in the unlocked position.
A significant feature of the present invention is that the flexible hose system does not include components installed on either the portable vehicle or the stationary tank. Since all of the components of the flexible hose system are part of the system which interconnects the conventional components provided on both the portable tank and the stationary tank, the flexible hose assembly may be certified as an assembly and then merely carried by the operator for use during loading and unloading.
A significant advantage of the present invention is that the flexible hose assembly is relatively economical to manufacture, is highly reliable, and avoids the cost of interconnecting system components with either the portable tank or the stationary tank. The invention also utilizes a conventional flexible hose, which the user may already have.
These and further objects, features, and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.